The concept of legitimacy is at the heart of the theory of power. It is essential to understand how a political power is built and how obedience is obtained among the population. We examine here the legitimacy of power for two of the most important political philosophies of classical China: Confucianism and Legalism. We show how a specific group of the population, the scholar-officials, play a specialised role in the two systems, acting as a legitimisation group. We further compare rites and laws as a way to obtain social order, and morality vs punishments as a way to obtain obedience. We conclude that the Confucianist system is less fragile than the Legalist, but also more oppressive, since it allows fewer personal choices to individuals